Grouping tables for bringing together packing units, such as cartons, shrink packs, trays and plastic boxes, constructed as roller conveyors, are well known. The packing units can be brought together in a two-dimensional formation (block formation, e.g., pallet layer). This is done by supplying the roller conveyor from one or a plurality of branch conveyors. The packing units are then turned as needed prior to or on the roller conveyor and mechanically arranged in the required position by means of stopping points. The arranged packing units are then pushed off the roller conveyor at a right angle to the transporting direction. The supply, arrangement and pushing-off of the packing units is treated as one cycle. For combining a layer, one or more cycles are necessary. A drawback in this known configuration is that gentle handling of the packing units is not ensured because the packing units roughly impact on the stopping points.
European Patent EP 1 465 101 B1 discloses an apparatus for row formation of packing goods for packing unit palleters. The packing unit palleter has at least one layering station and at least one palleting station. The row formation apparatus has at least one positioning station on which the packing goods are arranged in at least one row with desired gaps during transportation. The positioning station is coupled to a supply conveyor associated with the layering station. Upstream of the positioning station, at least one accumulating conveyor is arranged, wherein the positioning station comprises a plurality of conveying sections having controllable and feedback controllable drives, arranged one after the other in the transportation direction. The controllable and feed-back controllable drives enable the desired gaps to be formed in the packing goods. The row formation apparatus has at least one monitoring means for determining and monitoring the gap formation in the packing goods. The structure of the apparatus for forming a row for the layer in a pallet is complicated. A plurality of conveyors is necessary for achieving gap formation and/or for turning the packing goods.
U.S. Pat. No. 7,191,895 B2 discloses a system of conveyor belts for supplying articles to a sorting unit. Sensors are also provided for determining the position and/or alignment of the articles transported on the surface of the conveyor belt. The sensors are connected to a control unit which checks the entry of the articles into the sorting unit or controls the gap between the articles. The articles are not combined, however, for the layer of a pallet.
U.S. Pat. No. 6,812,426 discloses an apparatus enabling goods to be fed onto a further conveyor belt at a given interval, however, the act of palleting is not disclosed.
British Patent Application GB 2 253 826 A discloses an apparatus for combining articles to groups and then for packaging the articles of the groups. On a supply belt, the articles are supplied, each at a predefined interval, to a collecting conveyor, on which the groups are combined always of the same number of articles. The groups are then fed to a packaging apparatus with a subsequent belt.
European Patent Application No. 90103315.9 discloses a device for group formation and synchronizing of objects fed to a packaging machine. A flow compensation conveyor is provided for transporting the incoming objects and supplying them to a supply conveyor provided with bars arranged at equidistant intervals for separating groups of objects. Further, a first speedometer is provided, which can produce a signal proportional to the speed of the supply conveyor. A predetermined gap is adjusted with at least one correction conveyor driven by a speed-variable motor between the flow compensation conveyor and the supplying conveyor. The correction conveyor has an object position detector associated with it, which can emit a signal at the moment at which each article is placed on the correction conveyor, and has circuit means driven by the first speedometer and the object position detector to control the speed-variable motor. The device also comprises a bar detector, which outputs a signal whenever a bar passes the latter. The circuit means also comprises a connected microprocessor for each correction conveyor to obtain the signals from the bar detector, from the speedometer and from the object position detector for the associated correction conveyor and to supply a speed control signal to the speed-variable motor. The microprocessor is programmed to control the speed of the associated correction conveyor with respect to a basic value proportional to the speed of the supplying conveyor. In response thereto, this basic value is immediately changed by an additive correction constant proportional to the product of this basic value and the time difference of the signals output by the bar detector and the object position detector.
German Patent Application DE 10 2005 023 859 A1 discloses a grouping table for combining packing units, in particular shrink packs, for layer formation, comprising a continuously drivable conveyor, a step conveyor intermittently drivable and downstream of the conveyor, a layer formation station arranged adjacent to the step conveyor and a push-off means associated with the step conveyor and effective at right angles to the conveying direction, for group-wise transferal of the packing units to the layer formation station.
U.S. patent application Ser. No. 10/892,786 discloses a system for arranging packing units in a layer, which is ultimately placed or stacked on a pallet. Herein, three conveyor belts are linearly arranged. The packing units are provided to the apparatus via a first conveyor belt. The packing units are linearly arranged on the first conveyor belt. A second conveyor belt is used to separate the packing units. Subsequently, the packing units pass to a third conveyor belt, in which the arrangement of the packing units is carried out. All three conveyor belts run at different, but constant, speeds. After a layer is completely combined, the layer is transferred to the pallet.
Patent Specification EP 1 046 598 describes an apparatus for handling container packets, typically bottles or cans, for arranging them according to a predetermined configuration to enable transporting them to a pallet.
European Patent EP 1 578 680 B1 discloses an apparatus for arranging and orienting packets. First, a packet that is too fast is detected. Then the speed of a drive motor of a first conveyor is measured, on which the packet that is too fast is present. Then a counter is incremented as a function of the speed of the motor of the first conveyor. Reduction of the feeding speed is carried out with the help of the value assumed by the counter. Then the feeding speed of the second conveyor is increased as a function of the value assumed by the counter.
In packaging and palleting plants, as is well known, packets containing processed goods must be handled or aligned in lines, which serve the process or processing and are usually arranged upstream of the above mentioned handling station. This is necessary, in particular, in plants for handling containers for drinks, in particular cans and bottles of glass or plastic material, containing water, beer or wine. The packages in question can be, in particular, crates, cartons, packing units or clusters.
According to the state of the art, packing units are individually transferred from an allocating conveyor to a transportation conveyor. This means that, on the allocating conveyor, only one packing unit is transferred to the transportation conveyor at a time. This is done by handing over each individual packing unit individually to the transportation conveyor by means of a speed difference between the allocating conveyor and the transportation conveyor. Control is carried out by means of an arrangement of a plurality of light barriers.
To build up a transportation-safe pallet it is necessary to combine a plurality of packing units and/or packing unit groups to a batch. To be able to hand over a plurality of packing units at the same time as one batch from the transportation conveyor to the layer forming conveyor, they are first handed over from the allocating conveyor to the transportation conveyor in a stepwise manner, collected there and then handed over to the layer forming conveyor.
It has also been observed that the packing units are handed over from the transportation conveyor by intermittently traversing the layer forming conveyor in an individual manner. This means that for handing over a packing unit from the transportation conveyor to the layer forming conveyor, the layer forming conveyor is traversed in synchronism with the transportation conveyor by precisely one packing unit length in the conveying direction.
These batches can also be turned on the transportation conveyor depending on the layer formation and then handed over to the layer forming conveyor.
The state of the art has several drawbacks. When gaps are formed or the packing units are handed over between the allocating conveyor, the transportation conveyor and even the layer forming conveyor, the packing units are not handed over in an exact manner due to speed differentials and high accelerating and delaying ramps. The packing units are therefore often turned out of their predetermined positions. An important factor herein is also frictional resistance between the conveyor and the packing unit bottom surface. It is not possible to form an exact gap between the batches. In addition, there is also an energy loss arising from the distance to be traversed for the individual gaps in the batching process from the allocating conveyor to the transportation conveyor. This is how ultimately the time required for building up a pallet is increased.